BackForwardInstrument:  SESS/SSULI 

Instrument details
Full name SESS / Special Sensor Ultraviolet Limb Imager
Purpose Observation of the Extreme and Far UV radiation (vertical profiles) from the Earth's limb
Short description Spectrograph for observation of Far UV and Extreme UV in the spectral range 80-170 nm inclusive of the H Lyman-alpha line at 121.6 nm, with 1.5 nm resolution, stemming from atomic oxygen and nitrogen, and molecular nitrogen, resulting in direct measurements of the electron density vertical profile as well as ion and neutral densities
Background Part of the SESS (Space Environment Sensor Suite) package
Scanning Technique Limb scanning across the height range 50-750 km
Resolution Vertical: 4 km: horizontal 300 km (limb view)
Coverage / Cycle Global in 5 days for cells of 300 km side. Sampling at 90 s intervals
Mass Power Data Rate


Providing Agency NRL
Instrument Maturity Flown on operational programme
Utilization Period: 2003-11-20 to ≥2025
Last update: 2017-03-15
Detailed characteristics
Satellites this instrument is flying on

Note: a red tag indicates satellites no longer operational, a green tag indicates operational satellites, a blue tag indicates future satellites

Instrument classification
  • Solar and space environment monitors
  • Space radiometer or spectrometer
Mission objectives
Primary mission objectives
  • Aurora
  • Ionospheric plasma density
Secondary mission objectives
  • EUV flux spectrum
  • UV flux spectrum
Opportunity objectives
  • EUV sky image
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Tentative Evaluation of Measurements

The following list indicates which measurements can typically be retrieved from this category of instrument. To see a full Gap Analysis by Variable, click on the respective variable.

Note: table can be sorted by clicking on the column headers
VariableRelevance for measuring this variableOperational limitationsExplanation
EUV flux spectrum2 - very highNo specific limitation.Earth's limb observed, coarse spectral resolution
EUV sky image2 - very highNo specific limitation.Earth's limb observed, spectrometry with coarse spatial resolution
UV flux spectrum1 - primaryNo specific limitation.Earth's limb observed, high spectral resolution
UV sky image2 - very highNo specific limitation.Earth's limb observed, spectrometry with coarse spatial resolution
Aurora2 - very highNo specific limitation.Observed down to Earth's surface in UV (121.6-393.4 nm)